The invention relates to a vehicle seat with a) a seat carrier that receives a seat upholstery, with b) an underframe that is fitted with a longitudinal adjusting device with two couples of rails that are provided with a bottom rail and a seat rail each, and moreover with two front supports and two rear pivoting supports, a height adjusting mechanism being allocated to the rear pivoting supports, the front supports and the rear pivoting supports carrying the seat carrier and with c) a buckle of a safety belt that is connected to the underframe by way of a pull-type strap, so that tensile loads acting on the buckle are led into the underframe and wherein positioning means are furthermore provided for, said positioning means being assigned to the buckle and altering the position thereof upon height adjustment of the seat carrier.
With height-adjustable seat carriers it is state of the art to have the vertical position of the buckle of a safety belt adjusted subsequently. Reference is made to EP 0 265 747 B1 and to DE-A-32 16 015 which both disclose the features of a vehicle seat as set forth herein above.
In principle, these previously known devices have proved efficient. They also have found widespread use in practice. It is an object of the invention to indicate another solution for a buckle that follows the seat carrier in its vertical move. It is therefore a particular object of the invention to indicate such a buckle together with its component parts that is suited for a seat with integrated belt, i.e., that also permits a ferrule located at the other end of the lap part of a safety belt to be carried along. This communicated motion is to be synchronized for the two seat sides.
In view of the vehicle seat of the type mentioned herein above, the solution to this object is to provide the bottom rail neighboring the buckle with a side part that extends upward toward the seat carrier, to configure a slot in said side part, said slot being oriented substantially transversely to a direction of a belt load exerted by the belt buckle in the event of a frontal crash of the vehicle in which the vehicle seat is located, to provide for a sliding member which is guided in said slot and onto which the pull-type strap of the buckle is acting and to have the positioning means designed as a connecting rod that is attached on one side to the neighboring rear pivoting support and on the other side to the sliding member and that displaces the sliding member within the slot when the rear support describes a pivoting movement.
The position of the buckle is defined by the fact that the position of the sliding member inside the slot is altered when the seat carrier is being adjusted in height. As a result thereof, the buckle, which is firmly attached to the sliding member, is carried along in vertical direction. The sliding member is positioned in the slot by having it connected to the corresponding rear pivoting support by way of the connecting rod.
A very simple construction of a follower safety belt is made possible by the invention. This construction is extremely safe since the sliding member is guided within the slot and abuts direct on the slot without the need for any safety catch or safety contrivance whatsoever to intervene when the belt is loaded on account of an accident. The only point is that, in the event of an accident, the sliding member remains caught within the slot and that the corresponding components parts take all the belt loads occasioned by the accident. Accordingly, no safety contrivances whatsoever are to be overcome, such contrivances permitting the buckle to move freely first and being only destroyed or eliminated in another way in the event of an accident. Another advantage lies in the fact that the tensile loads of the belt are immediately led into the bottom rail to which the side part is connected.
In a preferred embodiment, the two rear pivoting supports are non-rotatably linked to each other by way of a tie bar. The other bottom rail, which is located on another side of the seat than the buckle, is provided with a side part that also has a slot with a sliding member, on which an end ferrule of a lap belt is acting, allocated thereto. This other seat side has a connecting rod as well. This configuration is particularly suited to so-called seats with integrated belt in which the lap belt is accordingly connected to the seat by its two ends. The motion of the two sliding members of each seat side within the respective slot is synchronized by the fact that the two rear pivoting supports are non-rotatably linked to each other by way of a tie bar.
In another advantageous embodiment, the slot describes a curve whose center is preferably located in a region located in opposite direction relative to the buckle. In other words, it is located in opposite direction relative to the direction of the belt load acting on the sliding member. In principle, the shape of the slot is purely one of choice. It may be adapted to the kinematics of the height adjustment. The shape of the slot is chosen to achieve an optimum position of the buckle in each and every single vertical adjustment position of the seat carrier.
In another advantageous embodiment, the rear pivoting support is on one side hinge-connected in a direct or indirect fashion to the corresponding bottom rail in a lower swivel joint and on the other side to the seat carrier in an upper swivel joint. The connecting rod is connected to the rear pivoting support at a hinge point that is located between the lower hinge point and the upper hinge point. By selecting the hinge point, the following height adjustment of the buckle may be kinematically optimized. Together with the shape of the slot that has just been mentioned, the selecting of a hinge point located nearer to the lower or to the upper hinge point of the rear pivoting support permits to achieve favorable kinematic properties.
It is furthermore advantageous to have each side part provided with two parallel lateral metal sheets that are both connected to the seat rail and are provided with their own slot each. Higher stability is thus achieved.
Furthermore, the sliding member is well guided thanks to the spacing of the two lateral metal sheets. In the event of an accident, tensile loads of the belt are favorably absorbed.
It moreover proved advantageous to non-rotatably connect the pull-type strap to the connecting rod. With a sliding member that is capable of rotating within the slot, this is achieved by the fact that the buckle cannot be rotated about the sliding member.
In a preferred development, the side part has a bearing means for directly fastening a seat back of the vehicle seat to the underframe. Thus, vehicle seats can be realized, in which a seat back is fastened directly to the underframe and in no case to the seat carrier. In principle, the invention is also suited to seat backs that are arranged on the seat carrier.